Sarcoma Vs. Adenocarcinoma in Cats

"Since I'm spayed, my chances of mammary cancer, an adenocarcinoma, are quite low."
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If your vet tells you that Kitty has sarcoma or adenocarcinoma, it is not good news. Both are types of cancerous tumors, but found in different parts of the body. Your cat's prognosis depends on various factors, including whether the cancer has spread.


Both sarcomas (also known as fibrosarcomas) and adenocarcinomas can affect felines, but in different ways. Sarcomas infiltrate the soft tissues, including muscle, cartilage, tendons, fibrous tissues and fat. The skin is its primary target, with sarcomas usually quite locally aggressive. Adenocarcinomas, on the other hand, affect glands and organs and are systemically aggressive.


Most cats diagnosed with sarcomas came down with this cancer because of a reaction to a vaccine. While it's not uncommon for an injection site to swell slightly after a shot, the area shouldn't remain swollen. If after three months, a lump persists, grows larger, or is the size of an olive or bigger, take your cat to the vet for an examination. According to, approximately 1 to 2 out of every 10,000 vaccinated cats develops this vaccine-related tumor. Those are very low odds -- the risk of your cat coming down with a disease because you failed to vaccinate him is much greater. Treatment includes surgical removal of the tumor, followed by radiation and chemotherapy. In order to reduce the number of vaccine-related sarcomas, major national veterinary organizations have developed guidelines for vaccine injection sites and inoculation frequency. The rabies and feline leukemia vaccinations are the most common culprits in vaccine-associated sarcoma.

Adenocarcinoma in Organs

Unlike sarcomas, adenocarcinomas aren't related to vaccinations. Adenocarcinoma tumors often appear in a cat's gastrointestinal system, but other common areas include the lungs and pancreas. According to the Connecticut-based Veterinary Cancer Center, it's important to remove the tumor even if it's metastasized, or spread to other areas, as cats treated surgically live longer. The center also recommends chemotherapy for the patient.

Glandular Adenocarcinoma

Glandular adenocarcinoma often appears in the salivary glands, where it quickly metastasizes to other areas of the body. Another type of adenocarcinoma affects female cats: mammary gland cancer. In cats, mammary gland cancer is the equivalent of breast cancer in women. If your cat is spayed, the odds of developing mammary cancer are extremely low, as long as she was spayed before the age of 2.


If your vet diagnoses a sarcoma before it becomes invasive, your cat might have a good prognosis. Rabies shots are given in the rear right leg, while feline leukemia vaccines are injected into the rear left leg; if your cat develops a vaccination sarcoma on either site, leg amputation can save his life.

The prognosis for most with organ-based adenocarcinoma isn't favorable because these fast-growing malignant tumors metastasize. If treated for organ-based adenocarcinoma, your cat might experience a good quality of life for a year or more. If a mammary adenocarcinoma is found early, before it is has spread, your cat can live for years after surgical removal of the tumor.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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